diff --git a/stdlib/2/ast.pyi b/stdlib/2/ast.pyi
index e4ba3b6f1..aff644337 100644
--- a/stdlib/2/ast.pyi
+++ b/stdlib/2/ast.pyi
@@ -1,7 +1,7 @@
 # Python 2.7 ast
 
 import typing
-from typing import Any, Iterator, Union
+from typing import Any, Iterator, TypeVar, Union
 
 from _ast import *
 from _ast import AST, Module
@@ -9,6 +9,7 @@ from _ast import AST, Module
 __version__ = ...  # type: str
 PyCF_ONLY_AST = ...  # type: int
 
+_T = TypeVar('_T', bound=AST)
 
 def parse(source: Union[str, unicode], filename: Union[str, unicode] = ..., mode: Union[str, unicode] = ...) -> Module: ...
 def copy_location(new_node: AST, old_node: AST) -> AST: ...
@@ -26,4 +27,4 @@ class NodeVisitor():
     def generic_visit(self, node: AST) -> None: ...
 
 class NodeTransformer(NodeVisitor):
-    def generic_visit(self, node: AST) -> None: ...
+    def generic_visit(self, node: _T) -> _T: ...
diff --git a/stdlib/3/ast.pyi b/stdlib/3/ast.pyi
index 241f874f1..69999dcac 100644
--- a/stdlib/3/ast.pyi
+++ b/stdlib/3/ast.pyi
@@ -1,16 +1,18 @@
 # Python 3.5 ast
 
 import typing
-from typing import Any, Union, Iterator
+from typing import Any, Union, TypeVar, Iterator
 
 from _ast import *
 
+_T = TypeVar('_T', bound=AST)
+
 class NodeVisitor():
     def visit(self, node: AST) -> Any: ...
     def generic_visit(self, node: AST) -> None: ...
 
 class NodeTransformer(NodeVisitor):
-    def generic_visit(self, node: AST) -> None: ...
+    def generic_visit(self, node: _T) -> _T: ...
 
 def parse(source: Union[str, bytes], filename: Union[str, bytes] = ..., mode: str = ...) -> Module: ...
 def copy_location(new_node: AST, old_node: AST) -> AST: ...